1. Technical Field to which the Invention Belongs
The present invention relates to a headlamp for a vehicle that is constituted to form a light distribution pattern for a low beam using a plurality of semiconductor light emitting elements as light sources.
2. Description of the Related Art
In a marker lamp for a vehicle such as a tail lamp, a light emitting diode is often used as the light source. For example, JP-A-2002-50214 describes a marker lamp for a vehicle in which a plurality of lighting units using light emitting diodes to be light sources are arranged.
In addition, JP-A-2001-266620 describes a headlamp for a vehicle which has such a structure such that a part of a plurality of light emitting diodes arranged in a matrix is selectively turned on to form a desirable light distribution pattern.
In the structure of the lighting unit described in JP-A-2001-266620, it is possible to change the shape of a light distribution pattern by dividing a region for turn on/off. However, it is hard to form a light distribution pattern with a desirable luminous intensity distribution.
On the other hand, it can also be supposed that the structure of a lighting unit in which a plurality of lighting units using light emitting diodes to be light sources are arranged as described in JP-A-2002-50214 is applied to a headlamp for a vehicle. In such a case, there is the following problem.
More specifically, if the same lighting units are simply used as described in JP-A-2002-50214, light distribution patterns formed by a light irradiation from the lighting units have pattern shapes and luminous intensity distributions which are identical to each other. Therefore, there is a problem in that the light distribution pattern of the headlamp for a vehicle which is obtained as a synthetic light distribution pattern cannot be formed with a desirable pattern shape and luminous intensity distribution. In this case, furthermore, it is very hard to form a light distribution pattern for a low beam having a cutoff line as the light distribution pattern of the headlamp for a vehicle.
The invention has been made in consideration of such circumstances and has an object to provide a headlamp for a vehicle having such a structure as to form a light distribution pattern for a low beam in which a light distribution pattern for a low beam can be formed with a desirable pattern shape and luminous intensity distribution also in the case in which a semiconductor light emitting element is used as a light source thereof.